Consider using a MAX232 anyway. The signals need to be inverted to be compatible with standard UART interfaces. So even if the protective diodes work, an inverter is needed to get the signals to the proper levels.
Jack B, W6FB On Jan 19, 2014, at 6:03 PM, Doug Faunt N6TQS +1-510-717-1197 <fa...@panix.com> wrote: > I'd been looking at cheap and dirty between another TTL level device to the > KX3 (I presume the KXPA100 is similar). The KX3 schematic looks as if the > putput may go as high as +12V, but a series resistor and diode clamp at +5V > should protect a TTL equivalent input. I used to know good values, but it's > been a long time since I messed with this. But a 2K2 series resistor, and a > Schottky diode clamp should win, but that's just what leaps to mind, please > check your application. > > Don has indicated that the significant circuit is an Elecraft "standard", but > I wouldn't mind getting verification that the KXPA100 is the same. > 73, doug > > > On 19-Jan-14 15:46, Don Wilhelm wrote: >> Jean, >> >> I mis-spoke. I do not have the schematic for the KAT500. but the >> circuit for the "RS-232" interface used in the XG3 has become sort of >> the standard at Elecraft as far as I know. I initially said it went to >> +5 volts, but after checking I see it can go to +9 volts. If your >> Ardrino TTL compatible sink cannot accept +9 volts without damage, you >> should use the RS-232 connection. It will work fine with relatively >> short cables (but not the very long cables supported by real RS-232 >> interfaces). >> >> 73, >> Don W3FPR >> >> On 1/19/2014 6:14 PM, F4GXG wrote: >>> OK, >>> In fact I planned to use a MAX232 because I though that it was necessary >>> for the kat500. >>> At the end it seems that the kat500 is TTL compatible, so it should be >>> easier to connect with an Arduino. >>> If I am right, a direct connection should be possible, without MAX232. >>> Anyone to confirm? >>> 73 Jean >>> 73 >>> >>> >>> >>> -- >>> View this message in context: >>> http://elecraft.365791.n2.nabble.com/KAT500-serial-cable-tp7579847p7583091.html >>> >>> Sent from the Elecraft mailing list archive at Nabble.com. >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:Elecraft@mailman.qth.net >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:Elecraft@mailman.qth.net >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
